1. Field of the Invention
This invention relates generally to transducer suspension systems and more particularly to a suspension system having a low profile.
2. Description of the Prior Art
Direct access storage devices (DASD), or disk drives, store information on concentric tracks of a rotatable magnetic recording disk. A magnetic head or transducer element is moved from track to track to record and read the desired information. Typically, the magnetic head is positioned on an air bearing slider which flies above the surface of the disk as the disk rotates. In some recently proposed disk drives, the slider (or carrier) rides on a liquid film or bearing on the disk. A suspension assembly connects the slider to a rotary or linear actuator. The suspension provides support for the slider.
The suspension must meet several requirements. The suspension must be flexible and provide a bias force in the vertical direction. This is necessary to provide a compensating force to the lifting force of the air bearing in order to keep the slider at the correct height above the disk. Also, the vertical flexibility is needed to allow the slider to be loaded and unloaded away from the disk. Another requirement of the suspension is that it must provide a pivotal connection for the slider. Irregularities in manufacture and operation may result in misalignment of the slider. The slider is able to compensate for these problems by pitching and/or rolling slightly to maintain the air bearing. Another requirement of the suspension is that it must be rigid in the lateral direction. This is needed to prevent the head from moving side to side, which would result in the head reading the wrong track.
Present suspension systems have problems in achieving low enough pitch and roll stiffness for the air bearing flying height tolerances while at the same time achieving high enough lateral stiffness to prevent relative motion between the slider and the supporting end of the suspension.
Another requirement of suspensions is that they have a radial frequency response that satisfies the requirements of the disk drive system. A desirable radial frequency response consists of resonances high in frequency and low in gain. The present suspension systems typically use flanged load beams which exhibit undesirable low frequency bending, torsion, and sway modes. This is especially true where the flange height of the suspension is relatively small.
Examples of suspension systems are shown in the following references:
U.S. Pat. No. 5,208,712, issued May 4, 1992; U.S. Pat. No. 5,172,286, issued Dec. 15, 1992; U.S. Pat. No. 5,138,507, issued Aug. 11, 1992; U.S. Pat. No. 5,074,029, issued Dec. 24, 1991; U.S. Pat. No. 5,063,464, issued Nov. 5, 1991; U.S. Pat. No. 5,012,368, issued Apr. 30, 1991; U.S. Pat. No. 5,003,420, issued Mar. 26, 1991; U.S. Pat. No. 5,001,583, issued Mar. 19, 1991; U.S. Pat. No. 4,996,623, issued Feb. 26, 1991; U.S. Pat. No. 4,996,616, issued Feb. 26, 1991; U.S. Pat. No. 4,991,045, issued Feb. 5, 1991; U.S. Pat. No. 4,937,693, issued Jun. 26, 1990; U.S. Pat. 4,853,811, issued Aug. 1, 1989; U.S. Pat. No. 4,884,154, issued Nov. 28, 1989; U.S. Pat. No. 4,868,694, issued Sep. 19, 1989; U.S. Pat. No. 4,807,054, issued Feb. 21, 1989; U.S. Pat. No. 4,167,765, issued Sep. 11, 1979; U.S. Pat. No. 3,931,641, issued Jan. 6, 1976; European Patent Application 484,906, published May 13, 1992; European Patent Application 442,225, published Aug. 21, 1991; Japanese Patent Application 01-213821, published Aug. 28, 1989; UK Patent Application 2,193,833, published Feb. 17, 1988; IBM Technical Disclosure Bulletin Vol. 33, No. 10B, March 1991, page 392; IBM Technical Disclosure Bulletin Vol. 32, No. 3A, August 1989, page 175; and IBM Technical Disclosure Bulletin Vol. 31, No. 12, May 1989, page 203.
Disk drives have become smaller in size while at the same time the data storage capacity has greatly increased. Large capacity disk drives typically have multiple disks mounted on the same rotatable spindle. In order to accommodate more disks in the same height, the space between each disk must be greatly decreased. Also, disk drives having only a single disk may have limited space to accommodate a suspension between the disk and an outer housing. The height of the suspension has proven to be a limiting factor in realizing closer disk spacing and smaller disk drives. What is needed is a suspension system having a very low profile which still meets the performance requirements.